This invention relates to plural plastic article shaping, and more particularly to handling such articles in a continuous manner on being sequentially released from the mold shaping surface.
Blow molding machines of the type consisting of a wheel mounted for rotation in a vertical plane having a plurality of molds about the wheel periphery are known in the art, e.g. U.S. Pat. No. 2,784,452. With this version of wheel machine, each mold station includes inner and outer mold sections and a hollow needle which enters the mold cavity after closing to puncture the wall of an enclosed pliable parison and expand it to form the article. At a preselected area along the path of mold travel, each outer section, with the article held therein, is drawn fully away from its inner section radially to the wheel axis, whereupon at an appropriate time it is ejected downwardly in the plane of wheel rotation.
Such a system possesses many molding advantages, but has presented problems from the standpoint of a reliable, troublefree system for maintaining positive control of the continuously ejected articles while moving them away from the machine, especially at high throughput rates. More specifically, space adjacent the wheel for locating takeaway components is at a premium because of system geometry. Conveyors cannot be in the plane of the wheel tangent to eject as with other types of wheel-molding systems, because each outer section in closing moves radially to the axis down through the plane where such a conveyor would be.
If it is elected to eject the molded parts while at elevated temperature before the plastic is well set in order, for example, to facilitate downstream deflashing, as described in commonly assigned applications A. and C. above, space must be maintained between adjacent articles or else they will stick together on touching and, as therein disclosed, a screw conveyor advancing articles while in a vertical attitude represents a viable approach toward such separation. Also, equal spacing between consecutive articles may be desirable to maintain timing with similarly spaced downstream stations for further processing the parts. Moreover, as mentioned in commonly assigned application B. above, it may be advantageous to provide for continued operation of one section of a continuous forming line while another portion is down for a reason inapplicable to the former, and this is especially true with respect to continuing to run rather massive wheel blow-molding machines of the type previously described.
An approach practiced in the prior art involves a pocket conveyor moving at 90 degrees to the plane of wheel rotation which in conjunction with additional differently oriented downstream conveyors, eventually present the articles to the next processing station. With such a system, however, it has proven difficult to accomplish one or more of the objectives, supra.